The present invention relates to improvements in mechanisms and methods for the manufacture of reclosable plastic bags and more particularly to an improved arrangement wherein a continuous sheet of film is prepared by attaching fastener elements to the surface thereof.
In the manufacture of plastic bags, various approaches have been used, some where the fastener profiles are integral with extruded thin plastic film material and others wherein the plastic profile strips are attached to the surface of the film. In most arrangements, the bags essentially are formed in side-to-side relationship with the fastener profiles extending parallel to the continuous strip of material. When this type of material is converted into bags on certain form, fill and seal machines, the fasteners will end on the wrong part of the bag, i.e., along the side instead of across the top. In order to provide a bag made in such an form, fill and seal machine, with the fastener across the top, it is necessary to position said fastener across the machine direction of the film.
Other procedures less frequently used have provided bags in end-to-end relationship whereby the continuous material can be rolled on a roll with the material of uniform thickness in the axial direction of the roll.
An object of the present invention is to provide an improved method and apparatus for the manufacture of material from which plastic bags are to be made employing a unique arrangement for the attachment of the fastener members with the members extending laterally across a continuous supply of bag material to provide material suitable for use in a form, fill and seal operation.
A further object of the invention is to provide an arrangement wherein separate and different coacting fastener strips can be attached to a continuous strip of material preparatory to forming reclosable bags from the material such as in a form, fill and seal operation.
A further object of the invention is to provide an improved apparatus and method wherein an improved bag material can be formed from which bags having reclosable tops can be made utilizing continuous rib and groove fastener members which extend laterally across the supply of bag material.
A feature of the invention is the provision of an arrangement whereby a continuous supply of thin thermoplastic film is advanced along a path and separate mating fastener elements are brought in laterally over the top surface of the film simultaneously from opposite directions to almost the film center and then attached to the surface of the film. The fastener strips are supplied off of rolls and cut to the desired length as they are fed onto the film. With this arrangement, the length of the fastener strips can be accurately controlled and their location on the film can be accurately controlled so that they will mate properly when the film is folded.
Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the claims, and drawings in which: